feat(access-logs): 日志明细支持按状态码筛选并折叠次要搜索项，修复首页来源分布无数据

- 修复 PostgreSQL/SQLite 日志库下首页「来源分布」卡片无数据：RegionCounts 对空
  节点 ID 误拼 node_id = '' 恒空条件，改为空节点 ID 表示全节点聚合（对齐 CH 语义），
  并过滤空白归属地
- /access-logs?tab=list 新增状态码筛选：状态码下拉含常用 2xx/3xx/4xx/5xx 选项，
  校验 100-599，非法值返回 400；ClickHouse 与 PostgreSQL/SQLite 日志库均支持
- 搜索框折叠：默认仅显示来源 IP 与状态码，节点 ID/访问域名/请求路径折叠进
  「更多筛选」

internal/model/analytics/filter.go

@@ -25,14 +25,16 @@ type NodeAccessLogFilter struct {
 	RemoteAddr string
 	Host       string
 	// Hosts exact-matches any host (case-insensitive). Prefer over Host for multi-domain scopes.
-	Hosts     []string
-	Path      string
-	Since     time.Time
-	Until     time.Time
-	Page      int
-	PageSize  int
-	SortBy    string
-	SortOrder string
+	Hosts []string
+	Path  string
+	// StatusCode filters by exact HTTP status code when > 0.
+	StatusCode int
+	Since      time.Time
+	Until      time.Time
+	Page       int
+	PageSize   int
+	SortBy     string
+	SortOrder  string
 }
 
 // NodeObservabilityFilter scopes ClickHouse node observability queries.

internal/model/openflare_observability.go

@@ -161,14 +161,16 @@ type OpenFlareAccessLogQuery struct {
 	RemoteAddr string
 	Host       string
 	// Hosts exact-matches any host (case-insensitive). Prefer over Host for multi-domain scopes.
-	Hosts     []string
-	Path      string
-	Since     time.Time
-	Until     time.Time
-	Page      int
-	PageSize  int
-	SortBy    string
-	SortOrder string
+	Hosts []string
+	Path  string
+	// StatusCode filters by exact HTTP status code when > 0.
+	StatusCode int
+	Since      time.Time
+	Until      time.Time
+	Page       int
+	PageSize   int
+	SortBy     string
+	SortOrder  string
 }
 
 // OpenFlareAccessLogBucketQuery filters folded access log queries (v1 stub).